The invention generally relates to pulse generating systems, and relates in particular to pulse generating systems for providing high voltage and/or high current rectangular pulses with an electrical transmission line.
Many analytical fields such as materials analyses, semiconductor testing, and radar and X-ray investigations require the use of rectangular, high speed, high voltage, high current pulses. Generating such pulses generally requires bulky, heavy and/or complex and costly equipment. While several techniques for generating pulses with transmission line pulse systems are available, they are typically limited in that their output voltage is equal to the charge voltage unless specially engineered lines or complex interconnection systems are employed. For example, a conventional technique for generating a quality pulse is with a transmission line pulse generator that charges a line from a source voltage and then connects the transmission line to a load. In most instances the pulse duration of existing transmission line is equal to or less than the electrical length of the line, tL=l/c where l is the physical length of the line and c is the propagation velocity of the transmission line. Transmission line systems, such as a Blumlein Transmission Line for example, typically either halve the voltage or halve the usable electrical length of the cable.
Soviet Patent No. SU 723769 discloses a pulse modulator that includes a high voltage source power source, a charger mechanism, a transmission line and a load. This reference discloses that the duration of the pulse on the load is equal to the electrical length of the line and the output voltage equal to the charge voltage.
U.S. Pat. No. 2,769,101 discloses a transmission line based pulse generator that can multiply the pulse output voltage into a load of specific impedance with a plurality of transmission lines. This system requires transmission lines of electrical lengths totaling multiple durations of the output pulse to develop higher voltages.
U.S. Pat. No. 5,138,270 discloses a pulse generator using a Blumlein circuit, a transmission line having twice the impedance of Blumlein lines, and a matching resistor to generate a pulse of 2 or 4 times the charging voltage. This system requires lines of differing impedances as well as transmission lines of electrical lengths totaling multiple durations of the output pulse.
In many applications where size, weight, and cost are concerns, it is desirable to provide a simple transmission line pulse generator using only half the electrical length of cable as its output pulse duration and is capable of driving an arbitrary load at up to twice the charge voltage. In addition, a system that may operate without extensive control and accurate switching is highly desirable, particularly in extreme environments where high reliability is required.
There is a need, therefore, for a transmission line pulse generation system that provides increased output voltage and/or pulse duration, yet is efficient and economical to produce, and is robust in relatively hostile environments.